Collapsible structures such as vestibules and tents are useful in a wide variety of applications for providing shelter and storage from the elements. Vestibules, for example, are frequently used in outdoor applications for sheltering and storing personal belongings, backpacks, cooking utensils, mobility devices, etc. from elements such as wind or moisture. These structures are generally available as either a stand-alone model for use independent of another structure, or as an adaptive structure configured to attach to an adjacent vehicle or structure. In certain models, the vestibules may have a modularizing feature that permits multiple structures to be attached together.
Entry into the collapsible structure is generally accomplished through an entranceway suitably dimensioned to permit access into or out of the interior of the structure. A door, panel, flap, screen, or other door mechanism equipped with a zipper, Velcro®, snap-fitting or other fastening means may be employed to seal the structure from the outside, or to block access to other connected structures (e.g. an adjacent vestibule, tent or vehicle). In some designs, the wall containing the entranceway may include a number of support members that provide additional strength for the collapsible structure. The collapsible structure may include, for example, several vertically oriented poles positioned along the wall containing the entranceway to prevent the wall from sagging or bowing from the weight supported above. In some designs, a raised lip or lower doorway edge is also employed to laterally tension the collapsible structure to reduce swaying or other horizontal motion that can affect the structural integrity of the structure.
Access through conventional door mechanisms can often prove difficult, particularly for individuals confined to a wheelchair, stroller, or other mobility device. The zipper, Velcro® or snap-fitting fasteners used by many prior art devices to seal the door mechanism are difficult and, in some cases impossible, to operate for those individuals who lack the manual dexterity to activate the fastener. In those designs employing a zipper, for example, the user must be capable of reaching along the entire perimeter of the entranceway to zip and/or unzip the zipper. This may pose a significant hardship for individuals confined to a mobility device since certain areas along the path of the zipper may be beyond the individual's reach. Moreover, the support members used to provide vertical and lateral support to the structure may, in certain cases, interfere with the wheels or feet of the mobility device as it enters or exits through the entranceway. As a result, there is a need in the art for a door mechanism that permits simplified and unobstructed passage through the entranceway of a collapsible structure.